Study of the functioning and importance of diffusers in Formula 1 cars

Abstract

This project focuses on explaining and understanding the functioning of diffusers and their importance in Formula 1 cars. Formula 1 car diffusers are the most unexplored elements in these vehicles, since their interaction with the ground show a non-understood flow behaviour. First, an explanation of the fundamental aerodynamic concepts that govern the aerodynamics of these vehicles is presented in order to understand how the flow works on diffusers and how relevant their use in aerodynamic load generation is. In addition, understanding these concepts is essential to analyze the results obtained in subsequent flow simulations and analysis. An extensive research about experimental and numerical information about motorsport diffusers is done. The geometry of diffusers is studied to know which is the optimum geometry that reaches high level of performance on this elements. The theoretical approach is principally based on [8] and [7] due to its highly understandable and clear content about motorsport diffusers. Once the functioning of diffusers has been analyzed and understood, CFD simulations of an approximate diffuser geometry are performed. The geometry simulated is the Ahmed body, a geometry that is used as a model that simulates the flow behaviour of motorsport diffusers. Three different Ahmed body configurations are performed: 0º diffuser, 25º diffuser and in the third case rear airfoils are added to the 25º diffuser Ahmed body. Simulation boundary conditions are determined taking into account the wall contour conditions. One of the parameters to be studied is the value of lift coefficient, which shows the aerodynamic load of the car, that is, the vertical force that causes the car to adhere to the ground and, hence improve cornering and acceleration performance. These analysis are performed with open-source CFD simulation software OpenFOAM©. Since there is no previous experience with this type of software, a stage of familiarization is done beforehand. An analysis of the results is done relating these results with the theoretical approach, as well as making a comparison between the 3 simulations. It is obtained that the 25º diffuser configuration generated more downforce than the 0º diffuser, which makes sense as the aim of adding a diffuser is to increase the amount of downforce produced. In addition, the 25º diffuser Ahmed body with the rear airfoils results in an substantial increase of downforce thank to the low pressure zone generated at the back of the body with the help of these airfoils. Finally, a study of the project costs will be performed as well as an environmental impact study.